Photosensitive Material Conveying System and Image Forming Apparatus

ABSTRACT

The photosensitive material conveying system is configured so that a feed out roller is contacted on a stack of sheets having a plurality of stacked photosensitive sheet films each of which is provided with an emulsion layer and a first protective layer provided on one side of a supporting base and a second protective layer provided on the other side with matting agent dispersed in the second protective layer, and the topmost sheet film in the stack of sheets is fed out by the rotation of the feeding out roller, wherein the matting agent has a spherical shape, a hardness softer than the first protective layer, and particle diameter in the range of 8 to 12 μm, and the contact pressure of the feeding out roller is 0.49 N/cm or less.

TECHNICAL FIELD

The present invention relates to photosensitive material conveying systems that feed out using a feeding out roller a plurality of photosensitive sheet films that have been stacked, and to image forming apparatuses.

BACKGROUND OF THE INVENTION

Thermal development apparatuses are known that execute a thermal development process of forming latent images on a sheet film made of a thermal development photosensitive material and making the images visible by developing using an application of heat, and sheet films stored in a storage container inside a thermal development apparatus are picked up for conveying and supplying the sheet films to the downstream side. In order to pick up such sheet films, although conventionally the suction cup method is used for lifting up the sheet films while adhering to them by vacuum suction, in this suction cup method, the time taken for picking up becomes long, and hence cannot be selected from the point of view of speedy processing of the thermal development process.

Because of the above reason, the feed roller method is desirable in order to minimize the time required for picking up films. In the feed roller method, a roller is contacted with the topmost sheet film and rotated thereby feeding out the sheet film (see, for example, Patent Document 1).

However, at the time of feeding out several sheet films stacked in a storage container using a feed roller, there was a problem that scratches could occur easily because the sheet film being fed out moves almost in parallel with being in contact with and rubbing against the sheet film below it.

Patent Document 1: Specification of U.S. Pat. No. 5,660,384.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

The present invention was made in view of the above problems in the conventional technology, and the purpose of the present invention is to provide a photosensitive material conveying system and image forming apparatus in which it is difficult for scratching of sheet films to occur while feeding out a plurality of stacked sheet films using a roller.

Means for Solving the Problems

In order to achieve the above purpose, the following finding was obtained as a result of keen study and investigation made by an inventor of the present invention about the causes that make scratches easy to occur in the sheet film at the time of feeding out, using a roller, a plurality of stacked photosensitive sheet films.

In other words, as has been shown in the schematic diagram of FIG. 7, photosensitive sheet films (hereinafter referred to merely as “films”) F1 and F2 have a thermal development photosensitive material Em coated on one surface of sheet shaped supporting base made of PET (polyethylene terephthalate), and, a first protective layer and a second protective layer made of cellulose are formed respectively on Em and on PET. PET has an elastic constant E of 3.92×10³N/mm² or more, the first and second protective layers made of cellulose have elastic constants of 3.14×10³N/mm² or more, and the thermal development photosensitive material Em is a soft mixed material. In the second protective layer, irregular shaped silica with an elastic constant about 2.94×10⁴N/mm² has been dispersed in the second protective layer as a matting agent so as to make stacked films easy to separate, and a part of this silica is projecting from the surface BC of the second protective layer. In the condition in which the film F1 is stacked over film F2 with the surface BC of the second protective layer on the PET side of film F2 as the top surface and the surface EC of the first protective layer on the Em side of the film F1 as the bottom surface, by rotating a feed out roller in contact with the top surface of the topmost film F1, the film F1 is fed out by making it move relative to the film F2 in the horizontal direction H. Because of this relative movement, as is shown schematically in FIG. 7, since the irregularly shaped and also hard silica matting agent is projecting from the surface BC in the second protective layer on the PET side of film F2, this matting agent causes scratches on the surface EC of the film F2.

In view of this, as is shown in FIG. 6, by monodispersing truly spherical plastic particles with a particle diameter in the range of 8 to 12 μm made of PMMA with an elastic-constant of 2.94×10³N/mm² or less as the matting agent of the second protective layer on the PET side, with the elastic constant (2.94×10³N/mm² or less) of the matting agent (PMMA) being less than the elastic constant (3.14×10³N/mm² or more) of the first protective layer (cellulose), since the matting agent is softer than the first protective layer, when the feed out roller rotates and moves film F1 in the horizontal direction H relative to film F2 in the condition in which the matting agent projects from the surface BC and is in contact with the surface EC of the first protective layer, the possibility of the scratching the surface EC of the film on the matting agent contacting side gets reduced.

In addition, since the contact pressure of the feeding out roller on the film is 0.49N/cm or less, the force acting locally between the contacting films becomes small, and the possibility of the matting agent scratching the surface EC of the film on the contacting side gets reduced.

The present invention was made based on the above findings. In other words, the photosensitive material conveying system according to the present invention is a photosensitive material conveying system with a construction so that a feed out roller is contacted on a stack of sheets having a plurality of stacked photosensitive sheet films that are provided with an emulsion layer and a first protective layer provided on one side of a supporting base and a second protective layer provided on the other side with a matting agent dispersed in the second protective layer, and the topmost sheet film in the stack of sheets is fed out by the rotation of the feeding out roller, with the feature of the system being that the matting agent has a spherical shape, has a hardness that is softer than the first protective layer, has particles diameters in the range of 8 to 12 μm, and that the contact pressure of the feeding out roller is 0.49N/cm or less.

According to this photosensitive material conveying system, when feeding out a sheet film by contacting the feeding out roller on the topmost sheet film in a stack of sheets, it becomes difficult for scratches to occur on the sheet film, because the matting agent dispersed on the second protective layer has a spherical shape, has a hardness that is softer than the first protective layer, and has particles diameters in the range of 8 to 12 μm, and because the contact pressure of the feeding out roller is 0.49N/cm or less, the force acting locally between the contacting films becomes small, and the possibility of the matting agent scratching the surface of the film gets reduced.

In the above photosensitive material conveying system, it is desirable that the feeding out roller contacts the sheet film on the second protective layer.

Further, it is desirable that the feeding out roller has a prescribed width along a direction at right angle to the direction of conveying, and has a centerline adjusting function in order to make the contact pressure uniform over the entire width of the sheet film. By making the contact pressure uniform over the entire width of the sheet film, since the feeding out roller will not contact the sheet film unevenly along the width direction, it becomes difficult for scratches to occur on the sheet film.

Further, it is desirable that the photosensitive sheet film is a thermal development type photosensitive film, and that the matting agent is PMMA (polymethyl methacrylate).

The image forming apparatus according to the present invention has the feature that it is provided with the photosensitive material conveying system described above, exposes and forms images onto the fed out sheet films. According to this image forming apparatus, since it becomes difficult for scratches to occur on the sheet films due to the photosensitive material conveying system described above, it is possible to form images with a high quality.

EFFECT OF THE INVENTION

According to the photosensitive material conveying system and image forming apparatus according to the present invention, it becomes difficult for scratches to occur made on a plurality of stacked sheet films fed out using a roller, and it is possible to form images with a high quality.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view diagram showing schematically the important parts of an image forming apparatus of the thermal development type and that includes a sheet film conveying system according to a preferred embodiment of the present invention.

FIG. 2 is a front view diagram showing schematically a film conveying apparatus that feeds out films from a film storage tray section and conveys them towards the downstream side.

FIG. 3 is a front view diagram similar to FIG. 2 that schematically shows the relative positions (a) and (b) of the film and the separating claws inside the film storage tray section of FIG. 2.

FIG. 4 is a front view diagram showing schematically the centerline adjusting link mechanism that can be provided to the conveying roller 46 of FIG. 1 to FIG. 3.

FIG. 5 is a diagram showing schematically the result of the present preferred embodiment.

FIG. 6 is a schematic cross-sectional diagram of a film for explaining the effect of reduction of generation of scratches in the present invention.

FIG. 7 is a schematic cross-sectional diagram of a film for explaining the cause of generation of scratches in the conventional technology.

DESCRIPTION OF SYMBOLS 40 Image forming apparatus 45 Film storage tray section 46 Conveying roller (feeding out roller) 46a Link member 46b Fulcrum shaft 46c Balancer 47 Pair of conveying rollers 50 Temperature raising section 53 Temperature maintaining section 54 Cooling section F Film, photosensitive sheet film

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

Some preferred embodiments of the present invention are described in the following referring to the drawings. FIG. 1 is a front view diagram showing schematically the important parts of an image forming apparatus of the thermal development type and that includes a sheet film conveying system according to a preferred embodiment of the present invention.

As is shown in FIG. 1, an image forming apparatus 40 of the thermal development type is one that forms a latent image on a surface EC of a film F having, as is shown in FIG. 6, a surface EC which is a coating of a thermal development type photosensitive material on one side of a sheet shaped supporting base made of PET and a surface BC on the supporting base side that is on the side opposite to that of the surface EC, by exposing to a laser light L from an optical scanning exposure section 55 while conveying the film F in the auxiliary scanning direction, and then heats the film F from the side of the surface BC thereby developing and making the latent image visible, passes the film via a curved conveying path and discharges it at the top part of the apparatus, with the apparatus being configured to have a relatively compact equipment chassis 40 a so as to be of a desktop type that can be placed on a desk, etc.

The image forming apparatus 40 of FIG. 1 comprises, a film storage tray section 45 that stores a plurality of sheets of unused films F near the bottom part of the equipment chassis 40 a; a conveying roller 46 that picks up and conveys the film F at the topmost position in the film storing tray section 45; and a conveying roller pair 47 that conveys the film F from the conveying roller 46 towards the downstream side.

Further, the image forming apparatus 40 comprises, a curved surface guide 48 formed in the shape of a curved surface so that the film F from the conveying roller pair 47 is guided and is conveyed after almost reversing the direction of conveying; conveying roller pairs 49 a and 49 b for conveying the film F from the curved surface guide 48 in the auxiliary scanning direction; an optical scanning exposure section 55 for exposing the film F between the conveying roller pairs 49 a and 49 b by optically scanning it using a laser light beam L based on the image data thereby forming a latent image on the surface EC; and an optical reflection type or optical transmission type detection sensor 60 that is placed on the upstream side of the conveying roller pair 49 a for detecting the film F conveyed from the curved surface guide 48.

The image forming apparatus 40, further, comprises, with a temperature raising section 50 that raises the temperature up to a prescribed thermal development temperature by heating from the side of the surface BC of the film F on which a latent image has been formed; a temperature maintaining section 53 that heats the heated film F and maintains it at the prescribed thermal development temperature; a cooling section 54 that cools the heated film F from the side of the surface BC; a density meter 56 placed on the outlet side of the cooling section 54 and that measures the density of the film F1; a pair of conveying rollers 57 that discharge the film F from the density meter 56; and a film stacking section 58 provided in an inclined position on the top surface of the equipment chassis 40 a so that the film F discharged by the conveying roller pair 57 is placed on it.

As is shown in FIG. 1, in the image forming apparatus 40, from the bottom part of the equipment chassis 40 a towards above are provided in sequence, a film storage tray section 45, a board section 59, conveying a pair of rollers 49 a and 49 b, a temperature raising section 50, and a temperature maintaining section 53 (upstream side), and since the film storage tray section 45 is at the bottommost position and the board section 59 is between the temperature raising section 50 and temperature maintaining section 53, it is hard for it to get affected by heat.

In addition, the conveying path from the conveying roller pairs 49 a and 49 b of the auxiliary scanning direction to the temperature raising section 50 has been constituted to be relatively short, while the film F is being exposed by the optical scanning exposure section 55, the front edge side of the film F is subjected to thermal development heating by the temperature raising section 50 and the temperature maintaining section 53.

A heating section is constituted by the temperature raising section 50 and the temperature maintaining section 53, and heats the film F up to the thermal development temperature and maintains it at the thermal development temperature. The temperature raising section 50 has a first heating zone 51 that heats the film F on the upstream side and a second heating zone 52 that heats the film on the downstream side.

The first heating zone 51 has a fixed flat shaped heating guide 51 b that is made of a metallic material such as aluminum, etc., a flat shaped heater 51 c made of a silicone rubber heater, etc., that is in close contact with the bottom surface of the heating guide 51 b, and a plurality of opposing rollers 51 a that are placed so as to maintain a gap smaller than the thickness of the film F so that they can push the film F against the fixed guide 51 d of the heating guide 51 b and whose surfaces are made of silicone rubber, etc., that has thermal insulation characteristic compared to metal, etc.

The second heating zone 52 has a fixed flat shaped heating guide 52 b that is made of a metallic material such as aluminum, etc., a flat shaped heater 52 c made of a silicone rubber heater, etc., that is in close contact with the bottom surface of the heating guide 52 b, and a plurality of opposing rollers 52 a that are placed so as to maintain a gap smaller than the thickness of the film F so that they can push the film F against the fixed guide 52 d of the heating guide 52 b and whose surfaces are made of silicone rubber, etc., that has thermal insulation characteristic compared to metal, etc.

The temperature maintaining section 53 has a fixed flat shaped heating guide 53 b that is made of a metallic material such as aluminum, etc., a flat shaped heater 53 c made of a silicone rubber heater, etc., that is in close contact with the bottom surface of the heating guide 53 b, and a guide section 53 a made of a heat insulating material, etc., that is placed opposite the fixed guide surface 53 d formed on the surface of the heating guide 53 b so as to maintain a gap (slit) d between it. The temperature maintaining section 53 is constituted so as to be flat from the second heating zone 52 from the side of the temperature raising section 50, and is formed to have a curved shape with a prescribed radius of curvature from the middle towards the top part of the apparatus.

The film F is conveyed while being heated in the first heating zone 51 of the temperature raising section 50, because the film F conveyed from the upstream side of the temperature raising section 50 by the conveying roller pairs 49 a and 49 b, by being pressed against the fixed guide surface 51 d by each of the opposing roller pairs 51 a that are being rotationally driven, has its surface BC in close contact with the fixed guide surface 51 d.

In a similar manner, even in the second heating zone 52, the film F conveyed from the first heating zone 51, by being pressed against the fixed guide surface 52 d by each of the opposing roller pairs 52 a that are being rotationally driven, has its surface BC in close contact with the fixed guide surface 51 d and is conveyed while being heated.

Further, it is also possible to have a configuration in which a V-shaped groove section with its opening part facing up is provided between the second heating zone 52 of the temperature raising section 50 and the temperature maintaining section 53, and because any foreign matter from the temperature raising section 50 falls in the groove part, it is possible to prevent any foreign matter from entering the temperature maintaining section 53 from the temperature raising section 50.

In the temperature maintaining section 53, the film F conveyed from the second heating zone 52, in the gap dd between the fixed guide surface 53 d of the heating guide 53 b and the guide section 53 a, is heated (temperature maintained) by the heat from the heating guide 53 b, and passes through the gap dd due to the conveying force of the opposing rollers 52 a on the side of the second heating zone 52. At this time, the film F is conveyed while having its orientation changed gradually from being almost horizontal in the gap dd to being almost vertical, and moves toward the cooling section 54.

In the cooling section 54, the film F conveyed almost vertically from the temperature maintenance section 53 is conveyed towards the film stacking section 58 while having its orientation changed gradually from being vertical to an inclined orientation while coming in contact with and being cooled by the cooling guide surface 54 c of the cooling plate 54 b made of metallic material, etc., due to the opposing roller 54 a. Further, it is possible to increase the cooling effect of the cooling plate 54 b by making it have a heat sink structure with cooling fins. It is also possible to make a part of the cooling plate 54 b have a heat sink structure with cooling fins.

The cooled film F coming out the cooling section 54 has its density measured by a density meter 56, conveyed by the conveying roller pair 57 and is discharged to above the film stacking section 58. The film stacking section 58 can temporarily stack a plurality of films F.

As has been explained above, in the image forming apparatus 40 of FIG. 1, the film F, in the temperature raising section 50 and the temperature maintaining section 53, is conveyed with its surface BC facing the fixed guide surfaces 51 d, 52 d, and 53 d in the heated condition, and with its surface EC which is coated with a thermal development type photosensitive material in the freely exposed to air state. In addition, the in the cooling section 54, the film F is conveyed with its surface BC being cooled by coming into close contact with the cooling guide surface 54 c and its surface EC which is coated with a thermal development type photosensitive material in the freely exposed to air state.

Further, the film F is conveyed by the opposing rollers 51 a and 52 a so that the time of its passing the temperature raising section 50 and the temperature maintaining section 53 is less than 10 seconds. Therefore, even the heating time from temperature raising to temperature maintaining becomes 10 seconds or less.

Next, explanations are given about the film F. The film F, as same as shown in FIG. 6, is provided with a sheet shaped supporting base made of PET, a thermal development type photosensitive layer Em made by coating on one side of PET, a first protective layer made of cellulose formed on the thermal development type photosensitive layer Em, and a second protective layer made of cellulose formed on the other surface of PET. A plastic matting agent is dispersed in the second protective layer with the following conditions.

-   -   Material: PMMA (polymethyl methacrylate)     -   Matting agent shape: Truly spherical     -   Matting agent hardness: Elastic constant of 2.94×10³N/mm² or         less     -   Matting agent particle diameter: 8 to 12 μm     -   Matting agent dispersion: Monodispersion

As has been explained above, the matting agent dispersed in the second protective layer, in contrast with the shape of the conventional matting agent in FIG. 7 which is irregular that can easily cause stress concentration, has a truly spherical shape with a particle diameter within the range of 8 to 12 μm thereby reducing stress concentration, and also, while the elastic constant of the conventional matting agent silica is large (2.94×10⁴N/mm² or more), the elastic constant (2.94×10³N/mm² or less) of the matting agent (PMMA) is smaller than the elastic constant (3.14×10³N/mm² or more) of the first protective layer made of cellulose, and hence being softer than the first protective layer, and in addition, because the method of dispersion of the matting agent is monodispersion and not multiple dispersion that can cause agglomeration of matting agents, it is possible to satisfy the conditions of making the surface EC of the first protective layer difficult to be scratched. Further, monodispersion is dispersing particles with almost the same size.

Next, a film conveying apparatus suitable for an image forming apparatus 40 of FIG. 1 is explained while referring to FIG. 2. FIG. 2 is a front view diagram showing schematically a film conveying apparatus that feeds out films from a film storage tray section and conveys them towards the downstream side.

Although a film conveying apparatus 61 of FIG. 2 is provided with a film storing tray section 45, a conveying roller 46, and conveying roller pairs 47 of FIG. 1, in addition it is provided with a lifting mechanism that lifts up the plurality of sheets of film F placed in the film storage tray section 45.

In other words, as is shown in FIG. 2, the lift mechanism of the film conveying apparatus 61 is provided with a lifting plate 62 that can swing with one end part 62 a on the side of the film storing tray section 45 acting as the pivot and that lifts up the plural sheets of the film F in the upward direction indicated by the broken lines due to the swinging action along the direction S of swinging, and a lifting plate 63 that can swing pivoting around one end part 63 a on the side of the film storing tray section 45 and the other end part 63 b on the side of the lifting plate 62 and can move up or down the lifting plate 62 by the other end part 63 b due to the swinging movement.

The lifting mechanism, in addition, comprises a drive motor 67, a contacting cam section 64 with an oval shape that contacts the bottom surface of the lifting plate 63, a cog wheel 65 that swings this contacting cam section 64 around the rotating shaft 64 a, and a cog wheel 66 that swings due to the rotating shaft 67 a of the driving motor 67 and mates with the cog wheel 65.

The driving motor 67 swings and changes the inclination of the contacting cam section 64 via the cog wheel 66 and the cog wheel 65 so that, even if the films F get reduced after being delivered out one by one, the topmost film is always contacting the conveying roller 46. In other words, when the number of sheets of the film F is large, the contacting cam section 64 makes the longer side direction of the contacting cam section 64 be inclined so that it is almost horizontal, and the longer side direction of the contacting cam section 64 is made to be inclined more and more towards the vertical direction as the conveying progresses and the number of sheets of the film F decreases.

The conveying roller 46 is made of a rotating roller that is driven by a motor (not shown in the figure), contacts with the topmost film F in the film storing tray section 45, and feeds out a film F in the feeding out direction k shown by a broken line in FIG. 2 and conveys it toward the downstream side when it is driven rotationally.

The conveying roller pair 47 has a progressing roller 47 a that applies a progressing force in the direction of conveying to the film F fed out from the conveying roller 46, and a dispensing roller 47 b that moves in cooperation with the progressing roller 47 a and dispenses the film one at a time. When the conveying roller 46 feeds out several sheets of the film F, while the progressing roller 47 a applies a progressing force to the topmost film F, the dispensing roller 47 b rotates in a direction opposite to that of the progressing roller 47 a and feeds the films below the topmost film F in a direction opposite to the conveying direction and returns the films to inside the film storing tray section 45.

Next, the separating claws that separate the topmost film F at the time that a film is conveyed from the film storing tray section of FIG. 2 is explained referring to FIG. 3. FIG. 3 is a front view diagram similar to FIG. 2 that schematically shows the relative positions (a) and (b) of the film and the separating claws inside the film storage tray section of FIG. 2.

As is shown in FIGS. 3( a) and 3(b), the separating claws 81 are provided on the supporting plate 80 on the inside of the equipment chassis 40 of FIG. 1. The separating claws 81 are provided so that, along with the swinging motion of the lifting plate 62, they can contact by their own weights the leading edge at both corners of the topmost film F inside the film storing tray section 45.

When the film F is lifted up from the initial position of FIG. 3( a) by the lifting plate 62 in the direction of the arrow, not only that the conveying roller 46 comes into contact with the topmost film F as is shown in FIG. 3( b), but also the two separating claws 81 contact by their own weight the film F at the two corners. When the conveying roller 46 is rotated in this condition, an elastic deformed part with a projecting shape is formed in the neighborhood of the location where the separating claws 81 of the topmost film come into contact, and with the energy accumulated in this elastic deformation part as the cause, the topmost film is separated from 81 the sheets of film below. The configuration of such separating claws is publicly known, for example, from the Patent Publication of U.S. Pat. No. 3,666,885.

Further, the lifting plate 62 of the film conveying apparatus 61 of FIG. 2 stops swinging when it is detected using a position detection sensor (not shown in the figure) that the topmost film F among the sheets of film stored has arrived at the prescribed position. At this time, the conveying roller 46 swings pivoting around the pivoting shaft 46 b (FIG. 4) due to its own weight and contacts the topmost film F. Following the change in the position of the topmost film F due to conveying of a film, although the conveying roller 46 contacts with the topmost film, when the position of the topmost film F has changed by more than a prescribed amount (has become lower), the film separation and conveying is stopped, and the lifting plate 62 is made to swing again until the position detector detects.

Because of the above configuration, it is possible to control the linear pressure (film nipping pressure) on the film F to within a prescribed range of less than 0.49N/cm, and also, it becomes possible to contain film conveying track to within a prescribed range, and hence it becomes possible to carry out stable film separation and conveying without the generation of scratches.

As has been explained above, although the conveying roller 46 contacts the film F so that the linear pressure is 0.49N/cm or less, as is shown in FIG. 4, the conveying roller 46 described above has a centerline adjusting link mechanism so that the contacting pressure is uniform over the entire width of the film F (in a direction perpendicular to the surface of the sheet). In other words, the link member 46 a gives pivotal support to the conveying roller 46 at one end taking the pivoting shaft 46 b as the pivot, and by providing a balancer 46 c at the other end, it is possible to make uniform the contacting pressure of the conveying roller 46 on the film F. In addition, in FIG. 4, by changing the weight of the balancer 46 c, it is possible to adjust further the contact pressure of the conveying roller 46 on the film F.

When image data is input from and external source to the image forming apparatus 40 of FIG. 1 to FIG. 3, the film conveying apparatus 61 starts operating, the film F is lifted up by the lifting plate 62, the film F in the film storing tray section 45 is conveyed in the direction k in FIG. 2 because the conveying roller 46 rotates in the condition in which it is in contact with the topmost film F. Next, the film F is passed through the guide 48 by the conveying roller pair 47 and sent to the conveying roller pairs 49 a and 49 b and conveyed in the auxiliary scanning direction, and a latent image is formed on the surface EC of the film F by being optically scanned and exposed by a laser light beam L from the optical scanning and exposing section 55 based on the image data between the conveying roller pairs 49 a and 49 b. Next, the film F with a latent image formed on it is heated and thermally developed in the temperature raising section 50 and temperature maintaining section 53 thereby converting the latent image into a visible image, cooled in the cooling section 54, and is placed on the film stacking section 58.

The feeding out of the film F such as the above from the film storing tray section 45 due to the rotation of a conveying roller 46, makes it difficult for scratches to occur on the film F because the matting agent dispersed in the second protective layer of FIG. 6 has a truly spherical shape, a hardness softer than the first protective layer, and particle diameter in the range of 8 to 12 μm, and the contact pressure of the feeding out roller is 0.49N/cm or less.

In addition, because of the centerline adjustment link mechanism of FIG. 4, since it is possible to make the pressure of the conveying roller 46 on the film F constant over the entire width of the film F, and since it is not possible that the conveying roller 46 contacts the film F in a slant manner along the width direction, it becomes difficult for scratches to occur on the film F.

As has been explained above, since it becomes difficult for scratches to occur on the surface EC of the film F, it is possible to realize a high image quality in the visible images formed on the film F.

Example of Implementation

To begin with, the photosensitive film was prepared in the following manner. That is, the photosensitive film was prepared in a manner similar to that of the sample number 115 in the Implementation Example 1 described in lines [0480] to [0519] of the of the Unexamined Japanese Patent Application Publication No. 2005-107496 applied for by the present applicants. However, the matting agent “3-dimensionally cross-linked polymethyl methacrylate: PMMA, average particle diameter 10 μm, truly spherical shape, degree of monodispersion 10%” was employed in place of the matting agent (3-dimensionally cross-linked polymethyl methacrylate: PMMA, average particle diameter 5 μm) in the “BC layer protective layer coating liquid” described in line [0494].

After feeding out films using the above film as shown in FIG. 1 to FIG. 4, a solid image with a density 2 was formed, developed, and the transmission image scratches were visually measured using a high luminosity X-ray film viewer. The linear pressure conditions of the roller on the film at the time of feeding out the above film were set as follows.

1. The roller linear pressure was 0.08N/cm using two rubber rollers of 60 mm width when the load of the conveying roller unit was made to be 0.49N.

2. The roller linear pressure was 0.16N/cm using two rubber rollers of 60 mm width when the load of the conveying roller unit was made to be 0.98N.

3. The roller linear pressure was 0.33N/cm using one rubber roller of 30 mm width when the load of the conveying roller was made to be 0.98N.

4. The roller linear pressure was 0.49N/cm using one rubber roller of 30 mm width when the load of the conveying roller unit was made to be 1.47N.

While the results of the above implementation examples 1 to 4 are shown schematically in FIG. 5, no transmission scratches were found after the development process in the implementation examples 1 to 3, and transmission scratches were barely visible in the implementation example 4. In this manner, in a film in which a matting agent of PMMA plastic with truly spherical shape dispersed in the protective layer, it was possible to suppress almost fully the generation of scratches by setting the linear pressure of the conveying roller to 50 gf/cm or less.

In addition, while we carried out similar experiments with the two types of thickness of the first protective layer of 3 to 4 μm and 7 to 8 μm, the generation of scratches when observed visually using an X-ray film viewer was smaller in the latter than in the former. This is considered to be because, even if sharp dents (scratches) are formed in the protective layer, the surrounding protective layer gets pressed during the process of conveying up to the exposure position thereby softening the shape of the dents, or gets pressed and flattened by the opposing rollers in the thermal development section after exposure, when the finished film is viewed in an X-ray film viewer, it is difficult for the light of the viewer (the transmitted light) to scatter or diffract around the area of the projections, thereby making the dents difficult to be observed, and hence they are not recognized as scratches.

Although a preferred embodiment of the present invention was described above, the present invention shall not be construed to be limited to this preferred embodiment, and various modifications can be made within the scope of the technical concepts of the present invention. For example, an image forming apparatus 40 as shown in FIG. 1, can be configured as a medical laser imager that can output medical images on films by imputing medical image data to this apparatus.

In addition, although the entire image forming apparatus 40 of FIG. 1 was of a relatively compact desktop type, the sheet film conveying apparatus according to the present invention is not applicable only to desktop type image forming apparatuses, and it goes without saying that it can be used also in relatively large image forming apparatuses of the thermal development type, as for example, in stand alone types, etc. 

1. A photosensitive material conveying system which is configured so that a feed out roller is contacted on a stack of sheets having a plurality of stacked photosensitive sheet films each of which is provided with an emulsion layer and a first protective layer provided on one side of a supporting base and a second protective layer provided on the other side with matting agent dispersed in the second protective layer, and the topmost sheet film in the stack of sheets is fed out by the rotation of the feeding out roller, wherein the matting agent has a spherical shape, a hardness softer than the first protective layer, and particle diameter in the range of 8 to 12 μm, and the contact pressure of the feeding out roller is 0.49N/cm or less.
 2. The photosensitive material conveying system according to claim 1, wherein the feeding out roller contacts the sheet film on the second protective layer.
 3. The photosensitive material conveying system according to claim 1, wherein the feeding out roller has a prescribed width along a direction at right angle to the direction of conveying, and has a pressure adjusting function in order to make the contact pressure uniform over the entire width of the sheet film.
 4. The photosensitive material conveying system according to claim 1, wherein the photosensitive sheet film is a thermal development type photosensitive film and the matting agent comprises PMMA (polymethyl methacrylate).
 5. An image forming apparatus comprising the photosensitive material conveying system according to claim 1, the image forming apparatus forming an image onto the sheet film having been fed out. 